Extra-intestinal fistula is one of the serious complications of abdominal surgery and used to have a high morbidity and mortality rate. In recent years, the cure rate of fistula has increased significantly under the systematic treatment of Academician Li Jieshou and Professor Ren Jianan at our hospital (Nanjing General Hospital of Nanjing Military Region and PLA Institute of General Surgery). The second edition of Fistula (2002), edited by Academician Li Jieshou, is a guideline for the treatment of fistula.
1. Definition of parenteral fistula
An extra-intestinal fistula is a fistula that connects the intestine to the skin of the body and belongs to the category of gastrointestinal fistula. GI fistulas also include intestinal fistulas and fistulas of the stomach, pancreas, bile, rectum, and anal canal.
It generally refers to pathologic rather than medical enterostomies.
2. Classification of extra-intestinal fistulas
Tubular fistula: a fistula of varying length and curvature between the fistula and the external opening of the intestinal wall.
Labial fistula: the intestinal mucosa is ectopically turned and forms a lip with the skin. It is mostly due to a split or defective incision in the abdominal wall.
Discontinuous fistula: also called complete fistula, in which all or nearly all of the intestinal canal is broken and almost all of the intestinal contents flow out of the body through the fistula.
Single fistula, multiple fistulas: a single fistula with one internal port and one external port; multiple fistulas with multiple internal ports and multiple external ports.
High fistula, low fistula: The fistula is called high fistula if it is proximal and low fistula if it is distal to the jejunum at 100 cm of the flexural ligament.
High-flow fistula, low-flow fistula: If the amount of intestinal fluid flow is >500ml/24h, it is called high-flow fistula. If it is <500ml/24h, it is called a low-flow fistula.
3. Etiology
Traumatic: trauma, surgery, endoscopy, abortion, etc.
Non-traumatic: congenital, infectious, tumor, intestinal obstruction, etc. 4.
4. Pathophysiological changes
Endostasis imbalance: oxygen imbalance, water-electrolyte imbalance.
Malnutrition
Infection
MODS
5. Diagnosis
The presence of intestinal fluid, gas or food draining from the trauma, or the direct observation of ruptured intestinal canal from the trauma surface, with an outgrown intestinal mucosa, is the main clinical manifestation of intestinal fistula, and most of them are not difficult to diagnose. There are also a few fistulas with small holes, little or inconspicuous spillage, and only a small purulent sinus tract on the abdominal wall, resembling the manifestation of an anal fistula, which must be diagnosed clearly by oral bone char or pigment, fistulography and barium gastrointestinal imaging.
6. Assessment before treatment
6.1 Assessment of fistula
6.1.1 Preliminary understanding of the cause of the fistula, assessment of the type and location of the fistula, and recording of the flow.
6.1.2 CT, ultrasound, and other imaging examinations to understand the presence and location and size of the pus cavity and to understand any abnormalities or occupancy of the abdominal organs.
6.1.3 Imaging or barium enema to observe the morphology, site, size, course of the fistula, continuity of the intestinal canal, distal intestinal canal with or without obstruction, and abdominal/retroperitoneal pus cavity.
6.1.4 Biopsy of the fistula for the presence of tuberculosis and tumor.
6.2 Nutritional status assessment
6.2.1 Anthropometric measurements
Body weight, skin folds, arm circumference and grip strength indicators, etc.
6.2.2 Protein nutritional status
6.2.3 Immune function measurement
6.3 Major organ function assessment
Heart, lung, liver, kidney, brain, gastrointestinal tract, etc.
6.5 Infection assessment
Blood picture, blood bacterial culture, bacterial culture of pus/drainage fluid
6.6 Assessment of water-electrolyte and acid-base balance
6.7 Knowledge of comorbidities
6.8 Scoring
e.g. APACHE II score
7. Treatment
7.1 Correction of endostatic imbalance
Early in the course of an extra-intestinal fistula, the body may suffer from circulating blood volume deficit, water-electrolyte disturbances and acid-base imbalance due to loss of intestinal fluid and abdominal infection without appropriate management. This is more obvious in high or high-flow parenteral fistulas. At this time, the main focus should be on maintaining the endostatic balance of vital signs, water-electrolyte and acid-base balance.
Common endostatic imbalances include isotonic dehydration, hypokalemia, and metabolic acidosis. Due to the high volume of fluid supplementation, which exceeds the peripheral venous load, central venous placement is often required and also provides an avenue for parenteral nutrition. However, nutritional supplementation at this time is only to provide the basic substrate required by the organism, and too much can instead lead to metabolic disorders.
7.2 Surgical drainage and anti-infective treatment
With the resolution of endostasis and nutritional problems, the number of patients failing treatment has gradually decreased, and infection has become the main cause of death in patients with parenteral fistulas. In some cases, the pathophysiological changes caused by severe intra-abdominal infection (SIAI), which refers to the patient’s inability to confine it, leading to diffuse, persistent, and potentially fatal bacterial peritonitis, are significant, while further nutritional depletion, organism immunity Further depression and subsequent multi-organ dysfunction can make treatment difficult or even unsuccessful. Anti-infective treatment consists of adequate local drainage and systemic application of antimicrobial agents.
The main cause of infection in patients with extra-intestinal fistula is the leakage of intestinal fluid into the abdominal cavity, which fails to be effectively drained at an early stage. Therefore, drainage is the key to treating extra-intestinal fistulas and preventing abdominal infections. The drainage we apply is a drip double cannula (or a triple lumen tube, i.e., a double cannula with a water injection tube next to it). The routes of placement are ① via the original drainage route, i.e. removing the original drainage tube and placing the drip double cannula in the original way, for those with basic patency of drainage and no other abscess cavity; ② dissection placement, i.e. placing the drainage tube in the enterocutaneous fistula and other effective sites after dissection, cleaning the abscess cavity and necrotic tissue, and abdominal flushing, which generally requires >100 ml/kg of abdominal flushing, for abscesses with peritonitis and poor drainage. (iii) Placement via an infected fissured abdominal incision, provided the drainage tube can be placed in place and drainage is unobstructed.
Our clinical experience shows that the Lai’s double cannula developed by academician Lai Jieshou is the most fluid and effective drainage tube, and is one of our “magic weapons” in the treatment of extra-intestinal fistula, but of course the key is the doctor’s decision. In addition to draining intestinal contents and pus through flushing and negative pressure suction, it also serves as an abdominal debridement, removing necrotic tissue, pus moss and fibrin from the pus cavity at each change. Therefore, by observing the degree of fouling of the double trocars, the frequency of tube changes can range from several times a day to once every few days.
With effective drainage, the pus cavity and fistula gradually shrink and become a “controlled fistula”, i.e., the overflowing intestinal fluid is effectively drained outside the body, avoiding its flooding in the abdominal cavity and its stay on the skin of the tissue surrounding the fistula, and the abdominal infection and skin erosion of the abdominal wall are quickly controlled. Self-healing of the extra-intestinal fistula becomes possible with the formation of a tubular fistula.
Systemic application of antimicrobials is not mandatory in the presence of patulous drainage. In the case of poor drainage, systemic application of antimicrobial agents is ineffective. Surgical infections are different from medical infections, mostly mixed infections, without patulous drainage, relying solely on antimicrobial agents, seeing that there will just be and increase in bacterial resistance and alternating strains of bacteria.
7.3 Maintaining the function of vital organs
The common outcome before death from ineffective treatment of parenteral fistula is MODS, and avoiding and correcting organ dysfunction as much as possible is another fundamental measure to reduce the morbidity and mortality of parenteral fistula.
After admission, patients with parenteral fistula are firstly monitored by vital signs, blood gas analysis and biochemical examination to initially determine the function of vital organs and the severity of the disease. For those with normal organ function, the airway should be managed, good cardiac function should be maintained, ischemia and hypoxia of organs should be minimized, infection should be controlled, and systemic supportive therapy should be strengthened.
Acute respiratory distress syndrome (ARDS)/acute lung injury (ALI) is the most common form of organ insufficiency. Infection is one of the most common causes of ARDS. The excessive inflammatory response activates effector cells, and the inflammatory mediators they release cause lung injury. The typical symptoms are respiratory frequency
PaO2<8kPa and PaO2/FiO2<40kPa are the common clinical diagnostic basis. Mechanical ventilation is the main treatment.
Acute renal failure (ARF) due to parenteral fistula is mostly prerenal in nature, and renal function can be restored in most patients if renal perfusion is effectively restored in a timely manner. Correction of hypovolemia, appropriate diuretics and vasodilators are effective measures to prevent and treat ARF. In severe ARF, maintenance of water-electrolyte and acid-base balance and nutritional support are necessary, and hemodialysis can significantly reduce its morbidity and mortality rate.
Cardiac insufficiency is mainly related to the decrease of blood volume, the increase of circulatory load and sepsis. It manifests as panic, shortness of breath, tachycardia and irregular heart rate, and rales can be heard in the lungs early in the treatment of parenteral fistula, which often requires large amounts of water and electrolyte supplementation and should be maintained at an appropriate rate. Patients with combined shock should be infused rapidly to correct shock quickly and prevent myocardial ischemia; patients without shock should not be infused too fast or at a controlled rate with monitoring of central venous pressure. The application of oxygen, cardiac stimulants, diuretics and vasodilators are commonly used treatments.
The causative factors of hepatic insufficiency are mainly impaired cellular energy metabolism due to hypoperfusion and cytokine release due to endotoxemia aggravating hepatocyte damage, and sometimes, long-term PN can also lead to hepatic insufficiency due to biliary sludge. The main manifestations are elevated levels of serum bilirubin and liver enzyme profiles and decreased hepatic-derived coagulation factors. Improvement of tissue oxygenation, hepatoprotective drugs, insulin, and adrenocorticosteroids are the basic measures of treatment. The liver is the most important metabolic organ of the body. In hepatic insufficiency, the metabolism of sugar, proteins, amino acids and fats will definitely be affected due to the degenerative necrosis of hepatocytes. In fact, the incidence of hepatic insufficiency complicated by parenteral fistula is not high, but when it occurs, the morbidity and mortality rate is quite high. Effective nutritional support is an important guarantee to reduce the mortality rate while eliminating the cause of the disease. The body should be supplemented with as much energy as it needs, not too much, so as not to increase the burden on the liver. Albumin should not be imported too much, so as not to produce too much ammonia. Amino acids should be mainly branched-chain amino acids, with arginine and glutamine added appropriately. Insulin resistance in critically ill patients makes poor use of glucose, and fatty milk is an ideal parenteral nutrition preparation. Due to the closure of the mononuclear macrophage system by long-chain fat milk, inhibition of T cells, impairment of liver function and incomplete oxidative metabolism, medium/long-chain fat milk should be used in patients with hepatic insufficiency. Enteral nutrition (EN) should be applied adequately in patients with good intestinal function, especially in patients with prolonged PN resulting in biliary sludge. In patients with coagulopathy, fresh frozen plasma (FFP), prothrombin complex and VitK1 can be transfused. after the above treatment, no improvement is seen, but instead hepatic encephalopathy develops, which often means the onset of the end stage of the disease.
The main manifestation of cerebral insufficiency is impairment of consciousness, which can be the inevitable end of the end stage. It can be the clinical manifestation of pulmonary encephalopathy, renal encephalopathy, hepatic encephalopathy, and can be caused by water-electrolyte disorders, acid-base imbalance, hyperglycemia, hyperthermia, or by cytokines and opioid peptides produced by the body after infection and stress. Treatment includes maintaining or correcting the stability of the internal environment, applying neurotrophic drugs, applying diuretics, adrenocorticotropic hormones to reduce cerebral edema, etc. For comatose patients, subhypothermia, hyperbaric oxygen and hyperalgesia treatment can also be tried. We found that naloxone, an opioid receptor antagonist, has a good hypnotic effect on cerebral insufficiency, and it also has an anti-shock effect on relieving respiratory depression.
Gastrointestinal insufficiency includes stress ulcers and intestinal insufficiency. The rate of gastric mucosal lesions in stress patients is as high as 75% to 100%. Stress ulcers are mainly caused by damage to the gastric mucosal barrier and H+ reflux, and treatment includes gastrointestinal decompression and acid control.
Intestinal insufficiency, which includes nutritional absorption disorders, motility disorders, and barrier dysfunction, is one of the major and most common organ insufficiencies in extraintestinal fistulas. The first two manifest as diarrhea and abdominal distention; the latter as bacterial translocation and endotoxin translocation. The intestine is the largest reservoir of bacteria in the body, and Meakins described the pathological state of the intestine as resembling an undrained pus cavity. carrico suggested that enterogenic infection is the initiating organ of MODS. The pathogenesis of enterogenic infections is attributed to imbalance of intestinal flora, damage to the intestinal mucosal barrier and suppressed immune function. In patients with MODS, maintenance of intestinal function is a key measure in determining prognosis. Treatment of intestinal insufficiency may involve the application of small amounts of dopamine, scopolamine and prostaglandin I2 to improve the perfusion and metabolism of the intestinal mucosa; more important is nutritional support aimed at enhancing the cellular proliferation and repair capacity of the intestinal mucosa. In the presence of abdominal infection and severe intestinal insufficiency, PN is necessary; when the intestine is working and can be used safely, enteral nutrition can be considered. Among enteral nutrition preparations, whole protein stimulates the renewal and repair of intestinal mucosa, which is stronger than amino acid or peptide formulations, but critically ill patients often lack complete digestive capacity, therefore, peptide formulations are more nutritious. In addition, the additional addition of certain substances, whether parenteral or enteral nutrition, is beneficial for the repair of intestinal mucosa and the healing of extraintestinal fistulae, such as glutamine, dietary fiber, n-unsaturated fatty acids, arginine and growth hormone.
7.4 Nutritional support
The daily secretion of digestive juices and shed cells from the small intestine contains nearly 70g of protein or 12g of nitrogen. Under normal circumstances, they are reabsorbed in the situation of amino acids and re-synthesized into protein. Patients with extraintestinal fistulas rapidly develop malnutrition due to infection, stress, loss of intestinal fluids and inability to eat. Malnutrition in turn can cause disorders of humoral and cellular immunity, increasing the risk of infection. This was the main reason for the high morbidity and mortality rate of extra-intestinal fistulas until the 1970s.
The loss of large amounts of intestinal fluid and high catabolism in the early stages of enterocutaneous fistula rapidly consumes the body’s stored nutrients, as well as the body’s structural and functional proteins. At this time, if given too much or even the normal amount of nutrition, can aggravate the damage to organ function, resulting in the occurrence of overfeeding syndrome. Overfeeding is potentially more damaging to the immune system than underfeeding. Therefore, the administration of nutrients should be gradually increased.
Early TPN has the effect of reducing gastrointestinal secretion, and water and electrolyte replacement and correction is simple and rapid. The composition of nutrients should also be mainly balanced, i.e., appropriate sugar, lipid and nitrogen ratios. At the same time, TPN can also be appropriately supplemented with glutamine and arginine.
Glutamine is a non-essential amino acid, and the need for glutamine increases in stress response conditions. Glutamine is also an important metabolic fuel for lymphocytes, and glutamine is required for the proliferation of lymphocytes. glutamine supplementation in TPN solution can improve the nitrogen balance and promote the growth of intestinal mucosa.
Arginine is a semi-essential amino acid that enhances wound healing and is a pro-secretor of many hormones, including growth hormone, as well as enhancing T-lymphocyte function.
However, parenteral nutrition also has shortcomings, such as ductogenic infection, intrahepatic bile, intestinal mucosal atrophy and bacterial translocation. Therefore, in the early stage of parenteral fistula, TPN is generally applied, and after the condition is stabilized, enteral nutrition (EN) is timely applied, which can be gradually transitioned from PN+EN to TEN. Because enteral nutrition has the advantages of promoting intestinal peristalsis, enhancing blood flow in portal system, promoting the release of gastrointestinal hormones, improving intestinal mucosal barrier function, reducing intestinal bacterial translocation and protecting host immune function.
The indications for the application of enteral nutrition are: abdominal infection control, unobstructed drainage of overflowing intestinal fluid, sufficient intestinal segments for digestion and absorption, and sufficient amount of bile, pancreatic juice and other digestive fluids mixed with nutrient solution. High enterocutaneous fistula can be injected with nutrient solution through a jejunostomy tube or by putting a catheter into the distal side of the parenteral fistula, while low enterocutaneous fistula can be injected with nutrient solution through a jejunostomy tube or a nasal intestinal tube. The nutritional formula is amino acids, monosaccharides, short peptides or whole protein preparations according to the intestinal function; or gradually transitioned as the intestinal function recovers and improves. In some cases, we also filter back the drained upper digestive fluid, which reduces the loss of body fluids and also ensures adequate digestion and absorption of nutrients.
Of course, in the early stage of extra-intestinal fistula, the application of growth inhibitor to reduce intestinal fluid secretion stage, it is not appropriate to apply enteral nutrition to avoid increasing intestinal fluid secretion. Enteral nutrition tube feeding method, should use feeding pump 24 hours continuous pumping, so as to promote the secretion of digestive juices to the minimum.
7.5 Application of growth inhibitors and growth hormone
In the early stage of parenteral fistula, the spillage of intestinal fluid causes fluid loss, abdominal infection and even bleeding, and reducing intestinal fluid loss is the key to promote self-healing of parenteral fistula. Growth hormone can reduce the secretion of digestive fluid, and some fistulas can heal spontaneously with effective drainage, TPN and growth hormone. However, most patients still have difficulty in healing, and malnutrition and poor tissue healing are the main causes. Promoting tissue growth and healing is the key to late treatment of fistulas. Under stress, protein catabolism is accelerated and synthesis is limited, so conventional nutritional support is not fully effective. Growth hormone promotes protein synthesis, incision healing and intestinal mucosal growth. This has led to the rapid treatment of extra-intestinal fistulas with a combination of nutritional support, growth inhibitors and growth hormone.
7.6 Definitive surgery
Surgical approaches can be divided into two main categories: control of abdominal infection and definitive surgical treatment. The former has been mentioned earlier.
Extra-intestinal fistulas are treated non-operatively and can partially heal spontaneously. For those who cannot heal spontaneously, definitive surgery should be chosen to close the fistula. Surgery is usually performed 3 months after non-surgical treatment, when the abdominal infection has been controlled, the local inflammatory edema has subsided, and the flow of the fistula has been significantly reduced. Indications for surgery also include chronic colonic fistulas, distal intestinal obstruction, inflammatory bowel disease, and intestinal malignancy, which cannot heal with nonoperative treatment and should be operated on early once identified. We have encountered two cases of extra-intestinal fistulas that occurred in our hospital after surgery for abdominal abscesses and were diagnosed as malignant lymphoma of the small intestine and sigmoid colon cancer, respectively, which were misdiagnosed or missed in outside hospitals.
Most of the patients with extra-intestinal fistulas have undergone intra-abdominal surgery or had severe abdominal infections, and therefore have varying degrees of intra-abdominal adhesions, which require extensive and careful adhesion separation during surgery. The surgical approach is based on partial resection of the intestinal segment, which not only closes the fistula, but also relieves the distal intestinal obstruction. The anastomosis is sufficiently free of the intestinal canal, with healthy tissue, good blood flow and no tension.
In cases where the adhesions are severe and it is not possible to separate the intestinal collaterals of the fistula, an open fistula can be performed. A short-circuit anastomosis of the distal and proximal intestinal collaterals where the fistula is located is performed to open up the collaterals where the fistula is located to restore bowel function and reduce leakage of intestinal fluid. This procedure is more commonly used for extraintestinal fistulas complicated by pathological intestinal diseases such as radiation enteritis, intestinal tuberculosis, and Crohn’s disease.
In some parts of the intestine, such as duodenum and rectum, enterocutaneous fistulas often have extensive adhesions and scar tissue, and it is not possible to isolate a larger segment of the intestine for enterocutaneous fistula anastomosis, which can be repaired with a piece of intestinal plasma muscle with a vascular tip.
The operation of intestinal fistula often requires extensive intestinal collaterals free, and there is a possibility of postoperative adhesive intestinal obstruction. Small bowel alignment fixation of the bowel is useful in preventing intestinal obstruction. Alignment fixation within the intestinal lumen cannula is a better method.
The peritoneal cavity should be cleaned with a large amount of saline at the end of the extra-intestinal fistula surgery, usually >100 ml/kg. postoperative drip double cannula drainage is usually applied to prevent abdominal infection.